1. Field of the Invention
The present invention relates to a band for a machine for producing web material, such as paper, board or tissue, and to a process for the production of such a band.
2. Description of the Related Art
In machines for producing web material, which is to say for example paper, board or tissue machines, bands which are permeable to air or steam for the extraction of moisture from the web material to be produced are used in various sections. Such bands, to be used in press sections or drying sections, for example, are frequently provided as woven bands in order to provide this necessary permeability, having longitudinal filaments running in a band longitudinal direction and transverse filaments running in a band transverse direction, the band longitudinal direction generally also corresponding to the direction of movement of the band. In order to be able to provide the bands in an endless configuration necessary for such machines, it is possible for example to provide the longitudinal ends of a band element produced in a weaving operation with projecting end regions, which is to say end regions not woven with weft filaments of the body of the band. These end regions of the longitudinal filaments projecting at the two ends of the body of the band are then woven with connecting transverse filaments in a connecting operation, so that a connecting zone is formed in which, although in principle a woven structure corresponding to the woven structure of the remaining body of the band with a corresponding bonding pattern is present, the ends of longitudinal filaments woven with the transverse connecting filaments still project. The filament ends are then shortened, so that they do not project substantially beyond the surface of the woven structure.
It has been shown that, primarily in the edge regions of such bands, there is the risk that the ends of the filaments shortened in this way will slip out of the fabric interspaces formed by the longitudinal and transverse filaments surrounding the ends of the filaments, so that frayed strips arise which have a visual appearance which corresponds to that of a ladder. The fact that this problem occurs primarily in the edge regions of such a band, which is to say those regions which do not come into contact with the web material to be produced, could point to the fact that this problem is thermally induced since, in these regions, cooling of the band heated in the production process by the web material to be transported onward is not produced. In addition, the action of cleaning liquid discharged from cleaning nozzles at comparatively high pressure could promote this slipping out of the ends of the filaments.
What is needed in the art is a band for a machine for producing web material, in particular paper, board or tissue, in which the problem of the filament ends slipping out is eliminated. Furthermore, a process for the production of such a band for producing web material is needed.